View Full Version here: : EQ Mounts
19-05-2012, 09:09 AM
hi, can someone please tell me how an EQ Mount works?
i thought all scopes had the same mounts...:confused2:
19-05-2012, 09:27 AM
Simply there is a coordinate system like latitude & longitude-that is called altitude (up down ) & azimuth (across)
An EQ mount does not sit flat though but is inclined to the sth or nth pole in the sky (SCP or ncp), when you move the two axis you are moving the eq mount in a diff coord system called ra & dec- you are moving it in an arc to locate the angle you want in the sky
19-05-2012, 09:51 AM
:thanx: Dannat, well that sounds a bit complicated, the scope i have at the moment is a refractor (only 70mm diameter) i have been using that for about 6 months & now i am looking at upgrading... what is an easy to use mount?
19-05-2012, 10:42 AM
In principle there are two types of mounts - Equatorial (EQ) and Altitude-azimuth (ALT-AZ). ALT-AZ must be familiar to you already - most of beginners refractors are sold with them. You find something in the sky as you would do with your eyes - looking around and up. EQ is different - in it's movements it follows the stars and planets. But needs some fiddly setup - no big deal if you learn how. The advantage of EQ mount is that it can be motorized easily so you can "stick" it to a star or, say, moon crater and watch it for a while not touching the mount handles at all.
19-05-2012, 10:58 AM
cool thanks Michael, i am buying a second hand reflector scope through E-bay which has a EQ mount... to learn how to use it what whould bw a good wasy? i was thinking you tube or just google it... any other recomandations?
19-05-2012, 11:17 AM
There are no fundamental differences between the various types of telescope mounts at all - they all rotate the scope about two orthogonal axes. However, those axes can be aligned differently with respect to the earth.
With an alt/az (or Dobsonian) mount, you aim the scope like you would aim a cannon, by rotating it in both a horizontal plane and a vertical plane. When you track a star, you must move it in both axes, since the star appears to move in both elevation and azimuth as the earth rotates.
In an Equatorial alignment, the "horizontal" plane of the alt/az mount is tilted using a wedge of some sort so that the axis of rotation is made parallel to the rotation axis of the earth. Then, when you track a star you only need to move the the scope in that axis (called the right ascension axis) to compensate for the rotation of the earth - you do not need to use the other axis (called the declination axis) at all ..... provided the mount is properly aligned.
The Eq alignment also removes the field rotation problem of an alt/az mount, which causes objects to appear to slowly rotate in the eyepiece as you track them. This means that Equatorial mounts are best for astro-photography.
However, if you are using a telescope with a side mounted eyepiece (eg a Newtonian), an equatorial mount can place the eyepiece in almost any position as you slew around the sky - and not necessarily one where you can put your eye - so an alt/az mount will be a better choice for visual use with such a telescope - this is the Dobsonian arrangement.
buying a cheap eq mounted scope would be an excellent way to understand how they work - a bit of messing around will be much more informative than words. And maybe read this http://members.optusnet.com.au/~beepa2/PDF%20Files/Aligning%20the%20Polar%20Axis%20of% 20a%20Portable%20Telescope.pdf
19-05-2012, 11:47 AM
Awesome, thanks Ray very helpful advise :2thumbs:
19-05-2012, 12:34 PM
:) I'd suggest heading to your local Astro Societies open night. There should be one on tonight somewhere close to you.
You'll be able to see all types of mounts and scopes up and running and be able to ask as many questions as like. :)
A couple of animation video's that may help you:
Equatorial Mount (http://www.spacetelescope.org/videos/eyes_skies_mount_eq/)
Altitude-Azimuth Mount (http://www.spacetelescope.org/videos/eyes_skies_mount_az/)
19-05-2012, 11:31 PM
One more advice - for a reflector on EQ mount an observing chair is a must. Cheaper version of it - a three step stepladder (30-40 dollars at Bunnings). See my avatar for it.
20-05-2012, 11:01 AM
:thanx: everyone for your comments :thumbsup:
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